The human body is composed of many types of tissues, not the least of which are bone, muscle, nervous, connective, circulatory and of course adipose tissue—more commonly known as body fat. For most people, the amount of certain types of tissues within the body, such as skeletal muscle and adipose tissue fat can be altered by choices in diet and exercise.
Although obesity is a growing problem in society at large, the reduction and elimination of all body fat is medically unsound. Indeed a healthy person will ideally have a balance of body fat, overall weight and lean tissue mass. Body Mass Index is also a widely recognized valuation of health and fitness and is often used and compared with body fat percentage in determining a variety of fitness and healthcare issues.
Indeed it has also been realized that muscle development and endurance is best established with yet again an ideal amount of body fat with respect to the person's weight and muscle mass.
Many methods of assessing a person's body fat and lean mass have been developed, such as but not limited to hydrostatic weighing, skin fold thickness measurements, and bioelectric impedance. But such methods have a number of drawbacks. Skinfold techniques involve an operator skillfully pinching the subject person's skin, without inducing pain, and measuring the thickens with a caliper. Moreover the operator must have reasonable skill in knowing how hard to pinch and where to pinch—factors that vary widely from one operator to another.
Hydrostatic weighing is perhaps the gold standard for determining body density and estimating body fat, and relies on the age old Archimedes' principle regarding the displacement of water by an object disposed in that water. Simply put, a person submerged in water will be buoyed by a counterforce equal to the weight of the water displaced. Muscle and bone are denser then water while fat is less dense—thus a person with a low percentage of body fat will have a higher body density and weigh more in the water then a person with a high percentage of body fat as weighed in the water.
But this process is not without issues. There must be estimation of pulmonary residual volume that may vary significantly from individual to individual, and even for an individual from one time to the next. High bone density also will tend to cause an underestimation of body fat while osteoporotic individuals are likely to see an overestimation. And of course hydrostatic testing requires a large facility, time and a person's willingness to get into the water.
X-ray and MRI imaging techniques may also be used, but of course there is a generally prevailing view that X-ray exposure should be limited so frequent use for body fat measurement may well provide more harm than benefit. And MRIs like hydrostatic testing require large facilities, time and willingness by the person to be placed into the system.
Ultrasound is an alternative form of body imaging which has shown some promise in a variety of areas including determining body fat. U.S. Pat. No. 5,941,825 to Lang et al. teaches a method involving at least two (2) different ultrasound pulses from two different locations and/or ultrasound devices having two (2) sources and two (2) detectors. With respect to both the Lang method and device, the difference in angle of the pulses is used to determine and reduce the parallax error. Of course this requires the ultrasound device to be properly positioned at the correct angle, which requires additional skill and training, or the use of a specialized device. In addition, it is noted that it is the signal that is analyzed for determination of body fat. Historical images or images that are generated principally for the imaging of other tissues are therefore not viable for processing as set forth by Lang.
U.S. Pat. No. 6,542,250 to Weber et al. provides a system for accurately measuring tissues thicknesses before, during and after a liposuction procedure which includes mapping adipose tissue thickness at key anatomical points. In one embodiment, the device comprises a remote control and data processing unit, a handheld ultrasound transducer, a monitor to display the information to the user and means to mark anatomical points of interest. Weber teaches, an ultrasound signal is transmitted into the tissue and the return signal collected. The collected signal is than communicated either through a direct wire connection or some wireless means, such as, RF, acoustic, or microwave to the remote control unit 20. The control unit 20 displays the recorded waveforms and calculated thickness of relevant layers. In addition, the control unit 20 stores the waveforms and information about the location of the measurement so that the user can easily monitor changes during the liposuction procedure. Again, this is strictly signal processing not image processing. Historical images or images that are generated principally for the imaging of other tissues are therefore not viable for processing as set forth by Weber.
Indeed there are a number of different US application and patents that have attempted to address the issue of determining body fat by ultrasound signal processing, and waveform analysis, but as noted with respect to Lang and Weber the reliance on signal processing or waveform processing is not the same as image processing and therefore entirely neglects both the possibility and the opportunity to use historical images or images that are generated principally for the imaging of other tissues.
Hence there is a need for a method and system that is capable of providing non-invasive determination of human body fat while overcoming the above identified challenges and or limitations.